The present invention pertains to phosphorus-containing oligopeptide derivatives which exhibit an angiotensin converting enzyme-inhibiting action and, thus, anti-hypentensive activity.
Heretofore, compounds typically represented by the formula: ##STR1## wherein Xa is CH.sub.2 or S, and Ra is hydrogen or benzyl, etc., have been known as phosphorus-containing peptide compounds having an angiotensin converting enzyme-inhibiting action (EP No. 0009 183 A1).
Compounds comparatively similar to the compounds of the present invention have been disclosed to have antibacterial activity in, e.g. GB No. 2030148A and Austrian Pat. No. 342192. These compounds are represented, for example, by the formula: ##STR2## wherein R.sub.A is hydrogen, methyl, hydroxymethyl, or mono-, di- or tri-halomethyl; R.sub.B is an .alpha.-amino acid residual group, etc.; R.sub.C is lower alkyl, lower cycloalkyl, lower alkenyl, aryl or aralkyl; R.sub.D is hydrogen or lower alkyl; and p is 1, 2 or 3. However, there is no suggestion in the literature that the compounds have an angiotensin converting enzyme-inhibiting action or hypotensive activity which is pharmacologically distinct from antibacterial activity.
Furthermore, certain phosphorus-containing oligopeptides which have an angiotensin converting enzyme-inhibiting activity and anti-hypertensive action are disclosed in commonly owned EP No. 0061172 A1.
However, new and better anti-hypertensive agents are in demand and, in this regard, novel phosphorus-containing oligopeptides of the present invention have been synthesized which exhibit enhanced angiotensin converting enzyme-inhibiting action and, thus, anti-hypertensive activity.